The present invention relates generally to electric communication between wayside installations next to a railway track by sending a signal through the running rails of the railway track.
U.S. Pat. No. 4,619,425 discloses an example of such electric communication. A solid state code transmitter and receiver device is located at each end of a railroad track section to alternatively transmit data codes through the rails to be received by the other end receiver element. One rail serves as the signal line while the other rail serves as the return path.
One of the main problems with this type of communication is that signals cannot be sent over long distances. Indeed, in case of poor weather or rail or ballast conditions, rail to rail current leakage as well as current leakage to earth will degrade a signal significantly over long distances.